1Unit-IVNano Technology 2(No Transcript) 3(No Transcript) 4SIZE A meter is about the distance from the tip of your nose to the end of your hand (1 meter 3.28 feet). Millimeter- One thousandth of meter.(10-3m) Micron a micron is a millionth of a meter (or) one thousandth of millimeter (10-6m) Nanometer A nanometer is one thousandth of a micron (109m) (or) a billionth of a meter. ie.,one billion nanometers in a meter. 5(No Transcript) 6

Composites made from particles of nano-size ceramics or metals smaller than 100 nanometers can suddenly become much stronger than predicted by existing materials-science models.

For example, metals with a so-called grain size of around 10 nanometers are as much as seven times harder and tougher than their ordinary counterparts with grain sizes in the micro meter range.

The Nano particles affects many properties such as

Melting point

Boiling point

Band gap

Optical properties

Electrical properties

Magnetic properties

.Even the structure of materials changes with respect to Size

7The properties of materials can be different at the Nanoscale for two main reasons First, Nanomaterials have a relatively larger surface area when compared to the same mass of material produced in a larger form. Nano particles can make materials more chemically reactive and affect their strength or electrical properties. Second, quantum effects can begin to dominate the behaviour of matter at the Nanoscale

One dimension It has only one parameter either length (or) breadth (or) height ( examplevery thin surface coatings)

Two dimensions- it has only length and breadth (for example, nanowires and nanotubes)

Three dimensions -it has all parameter of length, breadth and height. (for example, Nano Particles).

8What do you mean by Nano Particles ?Nano Particles are the particles of size between 1 nm to 100 nm

1 nm is only three to five atoms wide.

40,000 times smaller than the width of an average human hair

Nanometer - One billionth (10-9) of a meter

The size of Hydrogen atom 0.04 nm

The size of Proteins 1-20 nm

Feature size of computer chips 180 nm

Diameter of human hair 10 µm

At the nanoscale, the physical, chemical, and biological properties of materials differ in fundamental and valuable ways from the properties of individual atoms and molecules or bulk matter 9Why Nano Particles ?Noparticles are of interest because of the new properties (such as chemical reactivity and optical behaviour) that they exhibit compared with larger particles of the same materials. For example, titanium dioxide and zinc oxide become transparent at the nanoscale and have found application in sunscreens. Nanoparticles have a range of potential applications In the short-term application such as in cosmetics, textiles and paints. In the longer term applications such as drug delivery where they could be to used deliver drugs to a specific site in the body. Nanoparticles can also be arranged into layers on surfaces, providing a large surface area and hence enhanced activity, relevant to a range of potential applications such as catalysts. 10 Examples - Carbon Nanotubes - Proteins, DNA - Single electron transistors AFM Image of DNACarbon Nanotubes 11Nanotechnology deals with the creation of USEFUL materials, devices and systems using the particles of nanometer length scale and exploitation of NOVEL properties (physical, chemical, biological) at that length scale 12Various Nanomaterials and NanotechnologiesBased on the size and shape, the Nano materials are classified as follows Nanotubes Nanosprings Nanobelts Quantum dots Nanofluidies Nanoparticles Nanocapsules Nanofibers Nanowires Fullerenes (carbon 60) 13

Quantum well

It is a two dimensional system

The electron can move in two directions and restricted in one direction.

Quantum Wire

It is a one-dimensional system

The electron can move in one direction and restricted in two directions.

They can be made from a wide range of materials such as Semiconductor Nanowires made of silicon, gallium nitride and indium phosphide.

Nanowires have potential applications in

In high-density data storage, either as magnetic read heads or as patterned storage media

In electronic and opto-electronic Nanodevices, for metallic interconnects of quantum devices and Nanodevices.

Nanowires can be prepared by growth techniques such as

Chemical Vapour deposition (CVD)

Electroplating

19Quantum wire contIn quantum wire, Two dimensions are reduced and one dimension remains large Therefore, the electrical resistivity of quantum wire can be calculated using conventional formula as follows,We need two dimension to calculate area of conducting material, but not present in quantum wire 20

General properties of Nanowire

Diameter 10s of nanometers

Single crystal formation -- common crystallographic orientation along the nanowire axis

Cobalt nanowires on Si substrate(UMass Amherst, 2000) 22In quantum dot all the three dimensions are reduced to zeroQuantum dot 23Dimension Variation ? 24Properties of Nano Materials 25(No Transcript) 26Melting PointThe melting point decreases dramatically as the particle size gets below 5 nmSource Nanoscale Materials in Chemistry, Wiley, 2001 27Band gapThe band gap is increases with reducing the size of the particles 28Surface AreaThe total surface area (or) the number of surface atom increases with reducing size of the particles 29 Size-Dependent Properties of semiconductor and magnetic materials For semiconductors such as ZnO, CdS, and Si, the bandgap changes with size - Bandgap is the energy needed to promote an electron from the valence band to the conduction band - When the bandgaps lie in the visible spectrum, changing bandgap with size means a change in color For magnetic materials such as Fe, Co, Ni, Fe3O4, etc., magnetic properties are size dependent - The coercive force (or magnetic memory) needed to reverse an internal magnetic field within the particle is size dependent - The strength of a particles internal magnetic field can be size dependent 30(No Transcript) 31Applications of Nano Materials 321. Nanotechnology Applications in Medicine

Because of their small size, nanoscale devices can readily interact with biomolecules on both the surface of cells and inside of cells.

By gaining access to so many areas of the body, they have the potential to detect disease and the deliver treatment.

Nanoparticles can can deliver drugs directly to diseased cells in your body.

Nanomedicine is the medical use of molecular- sized particles to deliver drugs, heat, light or other substances to specific cells in the human body.

Nanoshells - that concentrate the heat from infrared light to destroy cancer cells with minimal damage to surrounding healthy cells.

Nanotubes- used in broken bones to provide a structure for new bone material to grow.

34Nano shells as Cancer Therapy Nano shells are injected into cancer area and they recognize cancer cells. Then by applying near-infrared light, the heat generated by the light-absorbing Nano shells has successfully killed tumor cells while leaving neighboring cells intact. 35(No Transcript) 36(No Transcript) 37Nanowires used as medical sensor

In this diagram (next page), Nano sized sensing wires are laid down across a micro fluidic channel. As particles flow through the micro fluidic channel, the Nanowire sensors pick up the molecular identifications of these particles and can immediately relay this information through a connection of electrodes to the outside world.

These Nanodevices are man-made constructs made with carbon, silicon Nanowire.

They can detect the presence of altered genes associated with cancer and may help researchers pinpoint the exact location of those changes

38(No Transcript) 392. Nano Computing TechnologyPast Shared computing thousands of people sharing a mainframe computer Present Personal computingFuture Ubiquitous computing thousands of computers sharing each and everyone of us computers embedded in walls, chairs, clothing, light switches, cars. characterized by the connection of things in the world with computation. 403. Sunscreens and Cosmetics

Nanosized titanium dioxide and zinc oxide are currently used in some sunscreens, as they absorb and reflect ultraviolet (UV) rays.

Nanocrystalline materials are candidates for separator plates in batteries because of their foam-like (aerogel) structure, which can hold considerably more energy than conventional ones.

Nickelmetal hydride batteries made of nanocrystalline nickel and metal hydrides are envisioned to require less frequent recharging and to last longer because of their large grain boundary (surface) area.

It has been shown that magnets made of nanocrystalline yttriumsamariumcobalt grains possess unusual magnetic properties due to their extremely large grain interface area (high coercivity can be obtained because magnetization flips cannot easily propagate past the grain boundaries).

This could lead to applications in motors, analytical instruments like magnetic resonance imaging (MRI), used widely in hospitals, and microsensors.

Nanoscale-fabricated magnetic materials also have applications in data storage.

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